Display screen or portion thereof for a transitional graphical user interface



FIG. 1 is a front view of a first image in a sequence for a displayscreen or portion thereof for a transitional graphical user interfaceshowing my new design;

FIG. 2 is a front view of a second image thereof; and,

FIG. 3 is a front view of a third image thereof.

The appearance of the transitional image sequentially transitionsbetween the images shown in FIGS. 1 through 3. This process or periodforms no part of the claimed design. The long and short dashed brokenline showing of a mobile terminal in FIGS. 1 through 3 forms no part ofthe claimed design. The mobile terminal, display screen, and the text,numbers, symbols and images of the transitional graphical user interfaceshown in broken lines in FIGS. 1 through 3 depict unclaimed subjectmatter, and form no part of the claimed design.

CLAIM I claim the ornamental design for display screen or portionthereof for a transitional graphical user interface, as shown anddescribed.